The food packaging technology is responding to the demand resulting from population growth and the rise of online food delivery services [1, 2]. According to European Bioplastics [3] the use of biopolymers in packaging accounted for 48% of the global biopolymer market, representing the largest application area in 2021.
Biopolymer films have gained attention in the food packaging sector not only for being more sustainable than synthetic polymers but also due to their barrier properties against gas exchange and maintenance of food product integrity [4]. Poly(lactic acid) (PLA), poly(butylene adipate-co-terephthalate) (PBAT), and poly(butylene succinate) (PBS) have gained prominence in the flexible packaging market, as evidenced by the increasing number of patents and articles [5, 3].
However, several issues are associated with these polymers. PLA competes for the production of starch-rich food crops such as corn and competes with the production of biofuels, utilizing arable land [6]. Although PBAT is biodegradable, its origin is petrochemical, making it non-renewable [5]. PBS can be obtained from fossil and renewable sources, but succinic acid, the precursor of this polymer, is also widely used in various applications, such as a surfactant in detergents, chelating agent to prevent corrosion in the electroplating industry, acidulant, pH regulator, and flavoring agent in the food and pharmaceutical industries [7].
Other noteworthy biopolymers originate from algae. Devadas et al. [8] state that the benefits of algal biopolymers over other biopolymers include high productivity, CO2 absorption, O2 release into the environment, and flexibility in cultivation. Additionally, algae cultivation has low costs as it does not require arable land compared to terrestrial crops, can be grown using wastewater, and does not compete with food production.
Films derived from algal polysaccharides, however, exhibit low water barrier properties, which limit their applications, particularly in the food industry [9]. Polymer coatings can be used to increase film hydrophobicity, such as low-density polyethylene, but in some cases, they are resistant to biodegradation, and their water vapor permeability may exceed that of coatings used in the food industry [10–12]. Some coatings used to enhance hydrophobicity in the field of food include vegetable oils, beeswax, candelilla wax, and carnauba wax.
Carnauba wax is derived from the powder extracted from the leaves of the Brazilian palm tree, Copernicia cerifera, and is mainly composed of a mixture of long-chain fatty acids and alcohols [13]. Moreover, according to the Food and Drug Administration (FDA), it is considered a generally recognized as safe (GRAS) substance, meaning it is safe for consumption in food products [14]. Approximately 55% of globally traded plant-based waxes originate from the carnauba tree, which is exclusively produced in Brazil. It has regional economic significance as it is produced only in the Northeast region and national significance as it is among the main products in Brazilian export, standing out among other waxes in terms of generated revenue [15].
Given the growing demand for food packaging highlighted by Ncube et al. [1] and Tyagi et al. [2], there is a clear need for more sustainable solutions in this market. Considering that the main biodegradable polymers either are non-renewable or compete with the food industry for arable land, exploring polymers derived from algae may offer a solution. The main challenge in utilizing algal polymers is their solubility in water. The present study hypothesized that an ulvan film produced with carnauba wax can be a sustainable alternative in the food packaging industry.
To test this hypothesis, the objective of this study was to analyze the effects of different levels of carnauba wax in biopolymeric films. The mechanical, chemical and physical properties of these films, as well as their solubility in water were evaluated.